The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e107da1b11c8418569fa52ee4e3d4d0feb60d027

commit e107da1b11c8418569fa52ee4e3d4d0feb60d027
Author: yuzus <yuzus@chromium.org>
Date: Fri Apr 01 09:18:58 2016

Implement ShadowRoot.mode

This CL implements ShadowRoot.mode, which returns open or closed for V1, and open for V0 shadowroots.

See the spec here: https://dom.spec.whatwg.org/#interface-shadowroot
BUG= 596770 

Review URL: https://codereview.chromium.org/1841353002

Cr-Commit-Position: refs/heads/master@{#384528}

[add] https://crrev.com/e107da1b11c8418569fa52ee4e3d4d0feb60d027/third_party/WebKit/LayoutTests/shadow-dom/shadowroot-mode.html
[modify] https://crrev.com/e107da1b11c8418569fa52ee4e3d4d0feb60d027/third_party/WebKit/LayoutTests/webexposed/global-interface-listing-expected.txt
[modify] https://crrev.com/e107da1b11c8418569fa52ee4e3d4d0feb60d027/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.h
[modify] https://crrev.com/e107da1b11c8418569fa52ee4e3d4d0feb60d027/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.idl